At present, it is common practice when applying crushed rock to a shoulder of a road, to utilize a dump truck which is driven along straddling the shoulder while the driver attempts to time the elevation of the dump body so as to deposit the desired amount of rock in the area of the shoulder. The control over the amounts applied vary widely, and part of the rock is deposited on the roadway, and part outward of the portion of the shoulder next to the roadway (such portion sometimes called hereinafter "adjacent shoulder"). The rock on the roadway must be removed, while that scattered over the shoulder beyond the adjacent shoulder is wasted. Even the portion of the rock deposited on the adjacent shoulder needs to be reworked, frequently by hand. The above procedure is obviously time consuming and wasteful.